Since the beginning of the 20th century energy has been a critical factor for armed forces worldwide. From the end of the Cold War to the first years of the 21st century, the U.S. Department of Defense’s (DoD) energy consumption dropped by some 40 percent, but with the Global War on Terror consumption has raised again.

In fiscal year 2009, the DoD consumed 932 trillion Btu of site delivered energy at a cost of 13.3 billion dollars. Energy consumed per active duty military and civilian personal is 35 percent higher than the U.S. energy consumption per capita, which is amongst the highest in the world. While consuming that amount of energy, DoD emitted 73 million metric tons of CO2, corresponding to over 4 percent of the total emissions in USA.

The DoD accounts for less than 2 percent of the US energy consumption and more than 93 percent of the U.S. government energy consumption. Although this may seem small, the fact is that DoD is the largest single consumer of energy in the United States. Nigeria, with a population of more than 140 million, consumes as much energy as the U.S. military.

On average, mobility fuels (for aircraft, ships, vehicles and equipments) have accounted for three quarters of the DoD’s total energy use over the past two decades. Buildings and facilities have made up the rest.

The U.S. is the strongest military power in the world and just like any other military in the world, energy, in particular energy derived from oil, is at the heart of that power. Oil accounts for nearly 80 percent of total DoD energy consumption, followed by electricity (11 percent), natural gas and coal. DOD pays immense effort for reducing its dependency on conventional oil and seeks ways to use alternative and renewable energy sources. Despite all these efforts, less than 4 percent of the DoD’s energy consumption comes from renewable sources.

The above graph breaks down energy consumption by the U.S. Military in 2009 based on data from DoD FEMRFY2009.

The DoD uses 360,000 barrels of oil each day. This amount makes the DoD the single largest oil consumer in the world. There are only 35 countries in the world consuming more oil than DoD. The U.S. Air Force is the largest oil consumer within the DoD services.

Less than half of DoD oil consumption occurs in the continental U.S., and the rest is consumed overseas. According to Sharon E. Burke, the Pentagon’s director of operational energy plans and programs, the Defense Logistics Agency delivers more than 170,000 barrels of oil each day to the war theaters, at a cost of $9.6 billion last year.

Although energy costs represent less than 2 percent of the DoD budget, indirect costs such as those for transporting fuel to battlefields and distributing it to the end-user add to the total. When the average American is paying $3 per gallon of gasoline, the price can soar to $42 a gallon for military grade jet fuel delivered through aerial refueling.

The military is aware of its dependence on energy. Defense Secretary Robert M. Gates identified energy as one of the department’s top 25 transformational priorities, and 2010 Quadrennial Defense Review addressed energy for the first time as a strategic issue. Although the DoD has already become a leader in some areas of renewable energy, it is yet to be seen whether it will be able to increase its energy efficiency and conservation, create viable alternatives and wean itself off oil.